1 Field of the Invention
This invention relates to a novel seat system for protecting the crew member of an aircraft from high "g" forces resulting from aircraft maneuvers and/or emergency ejection from aircraft while affording the crewmember a degree of mobility in the seat.
Modern high performance fighter aircraft are capable of flight maneuvers which subject the crewmember to very high forces of acceleration. Severe stresses are placed on the crewmember by such aircraft maneuvers. Fighter aircraft and their crewmembers have been lost as a result of pilot blackout resulting from aircraft maneuvers beyond the tolerance of the human crewmember. In addition, if a fighter aircraft is out of control or if an aircraft crash is imminent, the motion of the aircraft can be such as to make ejection of the pilot therefrom result in subjection of the pilot to ejection forces which are beyond his tolerance. Thus, in some emergency situations, ejection of the pilot from the aircraft in a conventional manner will result in severe injury or death.
2. Statement of the Prior Art
Some prior art methods of protecting the crewmember from the stresses of "g" forces require that the crewmember be placed in a prone position. This position purportedly enhances the crewmember's ability to tolerate "g" forces acting perpendicular to the spine resulting from many types of aircraft maneuvers. However, this prone position also hampers the pilot's visibility and may make it more awkward for the pilot to operate the controls. In addition, such a prone position makes it more difficult to safely eject the crewmember in the event of an emergency due to the dimensions of the seat required. The excessive length of the seat also increases the size of the crewmember/seat ejection envelope. This increases the size of the cockpit required to accommodate such systems. An example of a prior art seating system placing the pilot in a prone position is U.S. Pat. No. 2,369,258 to Shebat.
Other prior art seating systems for aircraft crewmembers provide the capability of altering the seating position (and sometimes the seating position angle as well) of the pilot or crewmember as required for various flight conditions. Such systems thus place the crewmember in a reclined position in order to enhance "g" tolerance resulting from certain aircraft maneuvers. Such systems also allow the crewmember to be in a nearly upright seated position when flight conditions require the crewmember to have good visibility and good dexterity for operating the controls. However, another disadvantage with such systems is that powering the seat to so alter its position increases the complexity of the system and its weight; moreover, movement of the seat to a desired position may not be fast enough to accommodate flight requirements, particularly under combat conditions or for ejection. Two examples of such prior art seating systems are U.S. Pat. No. 3,981,465 to Sinnett and U.S Pat. No. 4,004,763 to Bunnell.
Other prior art systems for providing the crewmember protection from "g" forces include strap restraints and cord systems for retaining the pilot or crewmember firmly against the seat. Such systems may use a pair of cords connecting the sides of the helmet to the shoulders of the pilot or crewmember. Another pair of cords are attached to the first pair and secured to a reeling in device at the back of the seat in order to pull the pilot's helmet and shoulders firmly against the seat upon the application of forces of acceleration. Such restraint systems may be unduly complex and severely limit the movement of the crewmember in the seat. An example of such restraint systems is U.S. Pat. No. 3,329,464 to Barwood.
Some prior art systems use a pad positioned over the chest of the crewmember to apply restraint directly to the crewmember's chest. However, such chest pads are functionally the same as and thus no more effective than the strap restraint system described hereinabove. Two examples of such prior art restraint systems using chest pads are U.S. Pat. No. 3,852,679 to DeLavenne and U.S. Pat. No. 4,300,799 to Cunningham.
A seat system is thus needed that will provide protection against compression of the vertebrae of the spine caused by high forces of acceleration resulting from ejection from the aircraft as well as aircraft maneuvers, while still allowing sufficient pilot mobility, good visibility, and good access to the controls.